The invention relates to extracorporeal treatment systems and methods, and particularly to verifying the connection of an extracorporeal circuit to an extracorporeal treatment assembly.
Extracorporeal treatment assemblies typically treat blood withdrawn from a patient and infuse the treated blood into the patient. These assemblies generally include an extracorporeal treatment apparatus having a pump or pumps, a blood treatment device and a separable extracorporeal circuit having blood and other liquid passages. The extracorporeal treatment apparatus may be a monitor for hemodialysis and hemo(dia)filtration and the treatment device may be a blood filter. The separable extracorporeal circuit may be a blood tubing set which attaches to the monitor.
Prior to a blood treatment session, an extracorporeal circuit is selected, mounted to the extracorporeal treatment apparatus and primed with a liquid. Priming generally involves flushing the passages in the extracorporeal circuit with priming liquid to purge gases from the passages. The blood treatment session commences after the circuit has been filled with the priming liquid and the gases flushed from the passages in the circuit. During the blood treatment session, the blood passages in the circuit may receive blood withdrawn from a patient, move the blood through a blood treatment device and infuse the treated blood into the patient. After the blood treatment session, the circuit may be removed from the apparatus and disposed of such as by being treated as medical waste.
An extracorporeal treatment apparatus may operate with various types of extracorporeal circuits. For example, an extracorporeal treatment apparatus may be configured to receive an extracorporeal circuit for normal sized adult patients, an extracorporeal circuit for pediatric patients, and a Low Weight Low Volume (LWLV) blood circuit for smaller adults. To start a blood treatment session, a human operator selects the type of extracorporeal circuit corresponding to the patient. The operator mounts the selected circuit to the apparatus. The operator may also enter operational settings for a desired treatment mode and information regarding the patient, e.g., normal sized adult, child or small adult, into the controller for the treatment apparatus.
The different types of extracorporeal circuits may differ in the sizes of their liquid flow passages circuit. The blood passages for the LWLV and pediatric circuits may have smaller diameters than the blood passages in a circuit for the normal sized adult. The difference in sizes of the passages affects the amount of liquid moved through the passage during each pump rotation.
The operational settings of the treatment apparatus cause the pump to rotate at rates intended to cause a certain rate of liquid to flow through the passages in the circuit. The operational settings for the extracorporeal treatment system may differ for each of the different types of circuits. For example, the pump speed may be faster for a normal sized circuit than for the LWLV circuit or the pediatric circuit.
If the wrong circuit is connected to the treatment apparatus, the operational settings may cause the pumps to withdraw or infuse blood and other liquids at rates different than the prescribed rates for the treatment. In particular, the rate of blood withdrawal or infusion may differ from the desired rates if the wrong type of blood circuit is connected to the treatment apparatus.
In view of the potential for the withdrawal or infusion of liquids at non-prescribed rates, there is a long felt need for an automatic process to detect whether the extracorporeal circuit connected to an extracorporeal treatment apparatus is the type of circuit that corresponds to the operational settings of the apparatus. Further, there is a long felt need for an automatic process to confirm or determine that an appropriate extracorporeal circuit is connected to an extracorporeal treatment apparatus.